In 2012, Norwegian oil and gas firm Statoil coined the phrase “subsea factory” and set out a vision to build such a system by 2020.
The goal is to enable longer step-outs in deeper and harsher environments. While the operator has been less vocal about the concept in recent years, the subsea factory concept has been put in motion and is driving new subsea technologies in Norway.
A significant step toward the subsea factory was made in 2015 with the launch of Statoil’s Åsgard subsea compression station offshore Norway. International conglomerates such as ABB, Siemens and Baker Hughes, a GE Company, are developing the subsea power infrastructure to support the subsea factory. But there’s a host of smaller Norway-based technology firms developing other subsea factory building blocks. These include subsea separation, water injection, the subsea Internet of Things (IoT) and resident subsea robotics.
Seafloor separation and subsea water injection are yet to be deployed on a permanent basis. Trondheim-based Seabed Separation is looking to provide a seafloor separation solution with its Dual Pipe Separator (DPS). Unlike conventional retention time separators, it separates the stream under flowing conditions—without the pressure losses seen in a conventional system—by using a set of fixed size, small separator pipes, the number of which can be varied according to capacity requirements. This means it’s smaller, lighter and more flexible than a conventional separator.
Removing produced water at the seabed would have a similar impact to boosting, according to Norwegian analysts Rystad, and the closer the system is to the wellbore, the more efficient the system will be, Seabed Separation CEO Asle Jostein Hovda said.
Seabed Separation has received support from Lundin, Wintershall and Aker BP as well as public funding to commercialize the concept. A full-scale pilot was successfully tested at Statoil’s Porsgrunn (or P-Lab) test facility near Oslo in 2017 using fluids from Statoil’s Troll Field at 30 bar with variable water cut and flow velocities. Seabed Separation has been working with Subsea 7 on project proposals, and it is looking to carry out onshore trials in either North America or the Middle East this year.
Seabox, developed by a Norwegian firm of the same name, which NOV acquired in 2015, could offer a solution for subsea seawater injection.
In February, NOV signed its first contract for the Seabox subsea water treatment system. A major operator plans to deploy the system in third-quarter 2018 for an extended offshore test. Seabox provides water treatment and then injection at the seabed, allowing operators to optimize waterflooding and improve oil recovery without the need to transport the fluids topside for treatment and reducing flowline and topside equipment requirements.
To connect, monitor and control these systems, easySubsea is creating easyComm, a subsea wireless network, working with Norway’s Odda Technology and Odda Digital Systems. “It’s going to be the introduction of IoT under water,” said Márcio de Alencar, managing director of easySubsea, which is the Norwegian arm of a Brazilian technology spin-off.
The project will develop a data acquisition and communication platform capable of performing the monitoring and control of subsea sensors and electrical actuators via a wireless subsea communication system. This will comprise two units: a data acquisition, conditioning and transmission/reception module for electrical sensors and actuators that will attach to the subsea christmas tree, subsea control module or manifold, and another module that will sit on the seafloor, under the host platform. The latter module is connected via an umbilical, acting as a connection hub.
Both modules couple to equipment that performs the wireless connection—a hydroacoustic modem or a laser modem. Power would be supplied by an interchangeable battery pack that would be changed by an ROV during well intervention to ensure continuous system functioning.
Just as using Seabox would reduce equipment requirements, easySubsea said its system would reduce capex and opex by making electro-hydraulic umbilicals obsolete.
Subsea power and communications infrastructure could also host resident subsea vehicles to monitor and maintain subsea equipment. Statoil is supporting projects to achieve this aim, including IKM Subsea’s RROV (resident remote operated vehicle). The RROV is a “permanently seabed installed” ROV controlled from onshore. IKM, based south of Stavanger, is using a Merlin UCV (ultra-compact vehicle) for an extended test, which had reached 50 continuous days of deployment in early March at 345 m water depth at Statoil’s Snorre B platform.
More futuristic maintenance concepts are also being developed. Trondheim’s Eelume has developed a snake-shaped underwater robot, without a tether, for subsea inspection tasks. The firm also has support from Statoil and Kongsberg Maritime.
The concept of the subsea factory is advancing with new technologies. Some may not be ready for Statoil’s 2020 vision, but the move toward an electrified subsea factory is underway.